Personal trainer Bryant Johnson is a records manager in Washington, D.C., federal court by day. In the evening, he is a personal trainer who counts Justices Ruth Bader Ginsburg and Elena Kagan among his clients.

Ginsburg has been training with Johnson since 1999 after she was treated for colon cancer. At the time, she was thin and weak, the Washington Post reports. “Now I’m up to 20 push-ups,” Ginsburg tells the newspaper.

Ginsburg is 80 years old and weighs little more than 100 pounds. But her push-ups are “old-fashioned, knees-off-the-ground push-ups,” the story says, and her exercise regimen also includes squats.

Ginsburg kept up her workouts even after treatment for a second cancer, this one affecting her pancreas. “I attribute my well-being to our meetings twice a week,” she told the Post. “It’s essential.”

Kagan has also benefited, the story says. She lost weight after becoming a justice through a change in diet and boxing sessions with Johnson.